Pressure gas operated switch with closed gas circuit



April l5, 1969 E A. FROWElN 3,439,140

PRESSURE GAS OPERATEDSWITCH WITH CLOSED GAS CIRCUIT Filed July 19. 1966 United States Patent Oce 3,439,140' Patented Apr. l5, 1969 3,439,140 PRESSURE GAS OPERATED SWITCH WITH CLOSED GAS CIRCUIT Egbertus Adrianus Frowein, Arnhem, Netherlands, as-

signor to Aktiengesellschaft Brown, Boveri & Cie,

The present invention relates to electrical switches, i.e. power circuit breakers and more particularly to those of the gas-blast type in which the breaker contacts are blasted with a compressed gas during the circuit interruption to extinguish the arc.

The invention is more particularly concerned with a gas-blast circuit breaker wherein the pressurized gas is caused to flow in a closed circuit and thus recuperated as distinguished from a breaker construction wherein the gas is used only once and then exhausted to atmosphere. In the circuit breaker to which the invention relates, the pressurized gas, for arc extinguishing, flows during the disconnection process from'a high pressure chamber through two hollow, nozzled shaped contact studs. Circuit breakers of the gas-blast type with dual nozzle type contacts have been known for a long time. Moreover, a gasblast circuit breaker is also known with a power interrupter contact actuated and blasted by the pressure gas, where the switching gases are blown into stagnation chambers and where devices are provided which shut oit temporarily the outflow paths from the stagnation chambers. The moving contact itself is designed as a shut-olf element. From the stagnation chambers the switching gas ilows, with a certain delay into the open air..The disadvantage of this arrangement is that the volume of the stagnation chambers is undesirably great for a predetermined blasting time, as it is necessary for the safe extinction of the arc. Accordingly the gas consumption is also high. Besides, a circuit breaker is known with extinction of the arc by pressure means, where the pressure shock caused in the surrounding gaseous medium by the discon nectingarc itself and the pressure wave respectively are used to extinguish the arc. The switch chamber is so designed that the pressure wave is guided in such a way that it strikes the arc again. This design is not suitable, however, for a gas blast circuit breaker with a closed gas circuit, particularly when SFS is used for the extinguishing gas. In this case there is the additional problem of keeping thedisintegration products of the switching gas caused by the arc away from the vital parts of the switch, since these disintegration products chemically attack the contact materials and can, in the form of dust or powder, block the moving parts from proper actuation.

In order to reduce, on the one hand, the gas consumption to a minimum, and on the other hand, to keep the switching gases for a certain time off the vital parts of the circuit breaker, the present invention provides a connection of the contact studs -on the outflow side with tubes closed at the end, which are under low pressure during the disconnection and which serve to ycollect the switching gases.

One suitable embodiment of the invention will be described in ldetail and is illustrated in the accompanying composite drawing the single view of which shows the circuit breaker in vertical central section, the structure to the left of the center line showing the contacts in closed position, and the structure to the right of the center line showing the contacts in open position.

With reference now to the drawing, 1 denotes a tubular insulator body within which is established a chamber 2 filled with high-pressure gas, in which are arranged the hollow nozzle-shaped, axially aligned contact studs 3 and 4. The driven contact stud 3 is rigidly connected at the same time with a cylinder 5 on which are articulated driving levers 6 and which is actuated in known manner by a drive, not represented here, to engage and disengage the other contact stud 4. The cylinder 5 is designed at its upper end as a valve seat and seals the high-pressure chamber 2 by means of the gasket 7 from the interior of the contact studs 3, 4, when the circuit breaker is in closed position, as represented in the left half of the figure. The contact studs 3, 4 are connected respectively with end closed tubes 8, 9 and are guided within the latter. The extension 10 of tube 8 protruding into the contact chamber 2 is designed as a double cylinder, the slotted and elastic lower part 12 of the cylinder 5 forming together with the outer tube 11 a sliding contact. The tube 11 has a ange 13 for mounting. The annular space 14 between the two tubes 10, 11 communicates, on the one hand, through the openings 15 with the interior of the tubes 8, l9, and on the other hand, by the interposition of the lter 16, with the surrounding low-pressure chamber part 21. The essentially stationary but resiliently mounted contact stud 4 is loaded by a conical spiral spring 17. The annular contact 18 which surrounds and engages the hollow contact member 4 serves to collect current. The current transmission, with the contact studs closed, is eiected by the contact stud 3 by means of the tulip contact 19 directly to the flange 20.

The method of operation is as follows: The contact stud 3, and thus also the tubular blast valve element 5 are moved downward by the drive, and not represented here, by means of the lever 6. While the contact stud 4 follows the driven contact stud 3 a small distance under the action of spring 17, the blast valve 5, 7 has already opened. At the same time, the contact stud 3 seals the openings 15. The connection to the surrounding low-pressure chamber is thus interrupted. In the course of the further contact movement, an arc 15 is drawn between the contact studs 3, 4. At the same time, two exhaust pressure waves enter the tubes 8, 9 respectively, are reflected at the closed ends of these tubes and arrive again at the nozzle ends of the hollow contact studs 3, 4. In general, the reflected pressure wave will have a value diierent from the pressure in the chamber 2 when it reappears at the nozzle end. After the blast, a compensation will take place between the gases in tubes 8, 9 and those in the chamber 2. In the meantime, the arc has been extinguished. In order to close the switching gap again, the contact stud 3 is moved upward. In the upper position, as shown in the left half of the drawing, the openings 15 are exposed so that the gas inside the tubes 8, 9 can escape into the low-pressure chamber, any impurities being trapped by the lter 16. In order to save space, the tubes 8 can have the form of a figure eight, instead of being straight, or they can have the form of two oppositely directed spirals.

With the circuit breaker embodiment according to the invention it is possible to reduce the volume to a minimum with a given blasting time, compared to a circuit breaker construction with simple intermediate vessels. Besides, the tubes 8 and 9 provide a large cooling surface and ensure rapid de-ionization and chemical recovery of the switching gases, Another advantageous possibility consists in lining the tubes with a material to bind the disintegration products.

I claim:

1. In an electrical circuit breaker of the gas-blast type,

the combination comprising means establishing a high` pressure chamber 4containing a pressurized gas and within which are located a pair of axially aligned 'hollow nozzled shaped contact studs, said contact studs being mounted for relative movement longitudinally of one another to cause their nozzle ends to become engaged and disengaged, a gas collection tube for each of said contact studs, each said tube being closed at one end and having the opposite end thereof connected with the end of the corresponding contact stud opposite the nozzle shaped end thereof, disengagement of said contact studs effecting a fiow of pressurized gas from said high pressure chamber into and through said contact studs into said tubes for temporary collection therein, and means establishing a communication between the interior of said gas collection tubes and a low pressure gas chamber only when said contact studs are re-engaged to permit flow of the collected gas from said collection tubes into said low pressure chamber.

2. An electrical circuit breaker as defined in claim 1 wherein said means establishing said communication between the interior of said gas collection tubes and said low pressure chamber is constituted by apertures in the wall of a movable one of said contact studs, said apertures being covered and uncovered respectively by movement of said contact stud away from and towards said other contact stud.

3. An electrical circuit breaker as defined in claim 1 wherein said gas collection tube correlated to a movable one of said hollow contact studs is constituted as a cylinder closed at one end and within which an end portion of said movable contact stud slides, the Wall of said cylinder including apertures which in cooperation with the sliding movement of said contact stud establishes a valve action closing off said apertures when said contact studs are disengaged and opening said apertures when said contact studs are re-engaged thereby to establish said communication between the interior of said gas collection tubes and said low pressure chamber.

4. An electrical circuit breaker as defined in claim 3 wherein said-cylinder gas collection tube correlated to said movable contact stud constitutes the inner cylinder of a double, concentric cylindrical structure, the exterior surface of the outer cylinder of said double cylindrical structure serving to guide said mova-ble contact stud, and the annular space between said inner and outer cylinders being in communication with said apertures in the wall of said inner cylinder thereby to serve as a passageway for the gas leading to said low pressure chamber.

5. An electrical circuit breaker as defined in claim 4 and which further includes a filter element located in said passageway and through which the gas must pass to reach said low pressure chamber.

6. An electrical circuit breaker as defined in claim 1 wherein said gas collection tubes have a rectilinear configuration, and are in axial alignment with said axially aligned hollow contact studs.

7. An electrical circuit breaker as defined in claim 1 wherein said gas collection tubes have a figure 8 configuration.

8. An electrical circuit breaker as -defined in claim 1 wherein said gas collection tubes have a spiral configuration.

References Cited UNITED STATES PATENTS 2,748,226 5/1956 Mac Neill et al. ZOO-148.4 3,290,469 12/1966 Leeds 200.148

FOREIGN PATENTS 1,160,061 12/1963 Germany.

ROBERT S. MACON, Primary Examiner. 

1. IN AN ELECTRICAL CIRCUIT BREAKER OF THE GAS-BLAST TYPE, THE COMBINATION COMPRISING MEANS ESTABLISHING A HIGH PRESSURE CHAMBER CONTAINING A PRESSURIZED GAS AND WITHIN WHICH ARE LOCATED A PAIR OF AXIALLY ALIGNED HOLLOW NOZZLED SHAPED CONTACT STUDS, SAID CONTACT STUDS BEING MOUNTED FOR RELATIVE MOVEMENT LONGITUDINALLY OF ONE ANOTHER TO CAUSE THEIR NOZZLE ENDS TO BECOME ENGAGED AND DISENGAGED, A GAS COLLECTION TUBE FOR EACH OF SAID CONTACT STUDS, EACH SAID TUBE BEING CLOSED AT ONE END AND HAVING THE OPPOSITE END THEREOF CONNECTED WITH THE END OF THE CORRESPONDING CONTACT STUD OPPOSITE THE NOZZLE SHAPED END THEREOF, DISENGAGEMENT OF SAID CONTACT STUDS EFFECTING A FLOW OF PRES- 